1. Field of the Invention
The present invention relates to a retractable wheel assembly for engagement with a trailer jackstand or the like to selectively permit transporting the trailer or immobilizing the trailer.
2. Description of Related Prior Art
Relatively light weight trailers usually have an extendable jackstand attached to the tongue, which jackstand includes a wheel to permit manual movement of the trailer. Heavier and/or larger trailers generally include a jackstand mounted on the tongue that has simply the end of a tube or a plate attached to the end of the tube for engagement with the ground. Such trailers are not manually moveable as the end of the jackstand or plate will not readily traverse the ground.
In order to hook up a trailer to a draft vehicle, the trailer may be manually moved into position if the jackstand includes a wheel. If there is no wheel, the draft vehicle must be maneuvered into a position to permit engagement of a latching mechanism at the end of the tongue with a ball attached to the draft vehicle. This is often a difficult and time consuming task, depending upon the skill of the driver.
Scaffolding often includes wheels mounted at the bottoms of the uprights to permit transport across the ground into position adjacent a building or the like. Generally, these wheels have mechanical friction locks to prevent unwanted movement of the scaffolding across the ground. However, depending upon the sophistication of the structure of the wheel supporting elements, rotational movement of the wheels about a vertical axis may occur. Sometimes the brakes are less than completely effective. Either of these problems create a safety hazard for personnel on the scaffolding.
Numerous other structures/apparatus require movement across the ground and a locking mechanism that can maintain the structure stationary on the ground. Furthermore, the transition from a stationary configuration to a mobile configuration must be relatively easy to accomplish and yet be essentially fail safe. To date, various apparatus exists for accomplishing these purposes but most suffer from various functional or structural impediments.